Marek Bouška

Hyaluronic acid (HA) is a natural biopolymer widely used in wound dressings for its supportive role in the healing process. In this study, we investigated the occurrence of microorganisms in chronic wounds and evaluated the antimicrobial activity of newly synthesized HA–Starch-based materials enriched with acidifying agents. Microbial isolates obtained from chronic wounds were tested for susceptibility using the agar diffusion method. The prepared materials exhibited significant antimicrobial activity against both reference strains and multidrug-resistant clinical isolates. Further characterization by scanning electron microscopy and elemental analysis confirmed uniform microfiber morphology and the expected elemental composition of the fibers. Cytotoxicity assessments performed using the xCELLigence system demonstrated the potential safety of developed materials. Overall, the results indicate that HA–Starch-based materials containing acidifying compounds exhibit strong in vitro antimicrobial activity against chronic-wound isolates, supporting their potential for further evaluation in wound care applications.

The reaction of organogallium amide LGa(NEt2)2 (1) and organotin carbonate L(Ph)SnCO3 (2), where L = 2,6‐(Me2NCH2)2C6H3, with organoboronic acids RB(OH)2 yielded molecular gallium‐ and stannaboroxines LM(O3B2R2) (3–8) (3: M = Ga, R = 4‐tBu‐C6H4; 4: M = Ga, R = 4‐CF3‐C6H4; 5: M = Ga, R = 3,5‐(CF3)2‐C6H3; 6: M = PhSn, R = 4‐tBu‐C6H4; 7: M = PhSn, R = 4‐CF3‐C6H4; 8: M = PhSn, R = 3,5‐(CF3)2‐C6H3). The Lewis acidity of boron atom (especially in 8) allowed to form N → B coordination bond with bases such as 4‐Me2N‐pyridine (DMAP) or poly(4‐vinylpyridine‐co‐styrene) (PVPS) yielding new compounds DMAP→8 (9) and PVPS→8 (10). The good film forming properties of 10 allowed the deposition of transparent thin layers by spin‐coating method and the determination of their hydrophobic properties by the sessile drop method. The study of hydrophobicity was subsequently focused on the content of stannaboroxine 8 in PVPS and on the concentration influence of the deposited PVPS:8 mixture solution. The parameters of thin layers such as thickness, transparency, and roughness were also determined.

This work addresses the possibilities of using synthesized novel magnesium complex dyes in zinc pigmented organic coatings based on epoxyester resin to reduce the zinc content in these coatings while maintaining or increasing the anticorrosive efficiency of them. The magnesium complexes Mg-Dye-I (C₃₄H₂₆MgN₈O₆), Mg-Dye-II (C₂₆H₁₉MgN₃O₅), Mg-Dye-III (C₁₇H₁₀MgN₂O₃), and Mg-Dye-IV (C₂₅H₁₈MgN₄O₆) with a series of azo carboxylate ligands were prepared from the diazo-coupling reaction of anthranilic acid with 5-methyl-2-phenyl-3-pyrazolone (Dye I; C₁₇H₁₄N₄O₃), anthranilic acid with naphthol AS-PH (Dye II; C₂₆H₂₁N₃O₅), anthranilic acid with 2-naphthol (Dye III; C₁₇H₁₂N₂O₃), and 2-amino-5-nitrophenol with naphthol AS-PH (Dye IV; C₂₅H₂₀N₄O₆). The synthesized novel magnesium complex dyes were characterized by analytical methods. Model coatings containing these dyes at pigment volume concentrations (PVCs) = 1, 3, 5 and 10% and zinc at a ratio of pigment volume concentration/critical pigment volume concentration (PVC/CPVC) = 0.60 were formulated to study the inhibitory properties of the individual synthesized magnesium complex dyes. Model coatings containing inorganic pigments (MgO and Ca-Mg-HPO₄) at PVCs = 1%, 3%, 5% and 10% and zinc at PVC/CPVC = 0.60 were also formulated. The coating pigmented only by zinc at PVC/CPVC = 0.60 was prepared as a standard organic coating. Corrosion resistance was also evaluated by potentiodynamic polarization studies and electrochemical impedance spectroscopy. The properties of organic coatings were also tested using other standardized and derived corrosion tests. In addition, the mechanical properties of the studied organic coatings were determined using standard tests. The aim of the work was to verify the possible synergistic efficiency of novel magnesium complex dyes by improving the mechanical, anti-corrosion, and chemical properties of zinc pigmented organic coatings.

Four new compounds from perylene dianhydride were prepared and tested for their anti-corrosion properties. Dizinc salt of perylene-3,4,9,10-tetracarboxylic acid and dimagnesium salts of perylene-3,4,9,10-tetracarboxylic acid, 5,5′-(1,3,8,10-tetraoxo-1,3,8,10-tetrahydroanthra[2,1,9-def:6,5,10-d′e′f′] diisoquinoline-2,9-diyl) bis(2-hydroxybenzoic acid) and N,N′-bis[3,3′-(dimethylamino)propylamine]-3,4,9,10-perylenediimide were characterized by analytical methods (SEM, EDX, X-ray) and parameters used in the field of paints (density, oil number and critical volume concentrations of pigment). The pigments (in a pigment volume concentration series) were used to prepare paints also containing a perylene C₂₆H₁₄N₂O₄ (Compound I) derivative pigment plus inert titanium dioxide to maintain a constant concentration of solids in the paint film. A mixture containing zinc nitroisophthalate and both the perylene derivative and titanium dioxide served as the reference material. The paints were applied to steel panels in two layers with a ruler. The organic coatings were subjected to electrochemical measurements and accelerated cyclic corrosion tests. The highest corrosion resistance was found for the coating containing C₂₄H₈O₈Mg₂. Superior to the coating containing either C₂₆H₁₄N₂O₄ or the conventional corrosion inhibitor C₈H₅N0₆-Zn, this pigment type acted mainly by a mechanism based on the compound’s complexation capacity at the metallic surface/organic coating/corrosion medium interface. The organic coatings containing perylene acid salts also attained high mechanical resistance.

A spectroscopic ellipsometry study on as-deposited and annealed non-stoichiometric indium zinc tin oxide thin films of four different compositions prepared by RF magnetron sputtering was conducted. Multi-sample analysis with two sets of samples sputtered onto glass slides and silicon wafers, together with the analysis of the samples onto each substrate separately, was utilized for as-deposited samples. Annealed samples onto the glass slides were also analyzed. Spectroscopic ellipsometry in a wide spectral range (0.2–6 eV) was used to determine optical constants (refractive index n and extinction coefficient k) of these films. Parameterized semiconductor oscillator function, together with Drude oscillator, was used as a model dielectric function. Geometrical parameters (layer thickness and surface roughness) and physical parameters (direct optical bandgap, free carrier concentration, mobility, and specific electrical resistivity) were determined from spectroscopic ellipsometry data modeling. Specific electrical resistivity determined from the Drude oscillator corresponds well with the results from electrical measurements. Change in the optical bandgap, visible especially for annealed samples, corresponds with the change of free carrier concentration (Moss–Burstein effect). Scanning electron microscope did not reveal any noticeable annealing-induced change in surface morphology.

Utilization of the N,C,N‐chelating ligand L (L={2,6‐(Me₂NCH₂)₂C₆H₃}⁻) in the chemistry of 13 group elements provided either N→In coordinated monomeric chalcogenides LIn(μ‐E₄) (E=S, Se) with unprecedented InE₄ inorganic ring or monomeric chalcogenolates LM(EPh)₂ (M=Ga, In). Complex LGa(SePh)₂ was selected as the most suitable single source precursor (SSP) for the deposition of amorphous semiconducting GaSe thin films using spin coating method.

Studies have been focused on the synthesis of N→Ga‐coordinated organogallium selenides and tellurides [L¹Ga(μ‐Se)]₂ (1), [L²Ga(μ‐Se)]₂ (2) and [L¹Ga(μ‐Te)]₂ (3), respectively, containing either N,C,N‐ or C,N‐chelating ligands L^1, 2 (L¹ is {2,6‐(Me₂NCH₂)₂C₆H₃}⁻ and L² is {2‐(Et₂NCH₂)‐4,6‐tBu₂‐C₆H₂}⁻) having Ga/E (E=Se or Te) atoms in 1/1 ratio. To change the Ga/E ratio, an unusual N→Ga‐coordinated organogallium tetraselenide L¹Ga(κ²‐Se₄) (4) was prepared. An unprecedented complex (L¹Ga)₂(μ‐Te₂)(μ‐Te) (5), as the result of the non‐stability of 3, was also isolated. Compound 2 is a suitable single‐source precursor for the preparation of amorphous GaSe thin films by the spin coating. Moreover, simple heating of an octadecylamine solution of 2 provided, after work up, monoclinic Ga₂Se₃ crystals with different crystallinity according to conditions used. Therefore, compound 2 may be also used as a source of Ga₂Se₃ in the low‐temperature doping process of Bi₂Se₃.

The reduction ability of a N→Sn coordinated distannyne {LSn}₂, where L is [C₆H₃‐2,6‐(Me₂NCH₂)₂]^– is tested towards organic molecules ethylene and cyclooctatetraene. These reactions provide the compound [{LSn}₃SnH] (2), as the result of a hydride abstraction. DFT calculations suggest that compound 2 can be interpreted as highly covalently bonded {HSn^I} and {(Sn^IL)₃} fragments. While the reduction of the C=C bond is not observed in the reaction of 1 with organic molecules, the reducing ability of 1 is observed in the reaction with inorganic SnO. Complex 1 is able to reduce SnO and the organotin(II) oxide {LSn}₂O (3) is obtained. Moreover, compound 3 is able to coordinate an excess of SnO to yield the organotin(II)–tin(II)–oxo cluster L₄Sn₁₀O₈ (4).

Laser desorption ionization using time-of-flight mass spectrometer afforded with quadrupole ion trap was used to study As₂Ch₃ (Ch = S, Se, and Te) bulk chalcogenide materials. The main goal of the study is the identification of species present in the plasma originating from the interaction of laser pulses with solid state material. The generated clusters in both positive and negative ion mode are identified as 10 unary (S_p^+/– and As_m^+/–) and 34 binary (As_mS_p^+/–) species for As₂S₃ glass, 2 unary (Se_q^+/–) and 26 binary (As_mSe_q^+/–) species for As₂Se₃ glass, 7 unary (Te_r^+/–) and 23 binary (As_mTe_r^+/–) species for As₂Te₃ material. The fragmentation of chalcogenide materials was diminished using some polymers and in this way 45 new, higher mass clusters have been detected. This novel approach opens a new possibility for laser desorption ionization mass spectrometry analysis of chalcogenides as well as other materials.